Silhouette of the domes and minarets of the Hagia Sophia and Hagia Eirene in Istanbul, Turkey.

Taken at dusk from a distance while on a cruise on the Bosphorus in Istanbul, Turkey. The silhouettes of the architectural marvels of the Hagia Sophia and the Hagia Eirene in Istanbul, Turkey, are mesmerizing. Built as churches during the Byzantine Empire they subsequently were converted into mosques under the Ottomans, first in Constantinople, the capital of the Byzantine Empire, which then became Istanbul, the capital of the Ottoman Empire, the only imperial capital in world history to serve as the capital of two successive empires.